Zhi-Qiang Shi

Syntheses, structures, and photoluminescent properties of a series of metal–organic frameworks constructed by 5,5′-bis(1H-imidazol-1-yl)-2,2′-bithiophene and various carboxylate ligands

A series of new metal–organic frameworks (MOFs), namely, {[Co(BIBP)(hfipbb)]}n (1), {[Co(BIBP)(Hbtc)]}n (2), {[Zn(BIBP)(5-OH-bdc)]}n (3), {[Cd(BIBP)(bdc)]}n (4), {[Zn2(BIBP)0.5(hfipbb)2]·H2O}n (5), {[Zn4(BIBP)4(bdc)4]}n (6), {[Zn(BIBP)(DL-ca)]·H2O}n (7), (BIBP = 5,5′-bis(1H-imidazol-1-yl)-2,2′-bithiophene, H2hfipbb = 4,4′-(hexafluoroisopropylidene)bis(benzoic acid), H3btc = 1,3,5-benzenetricarboxylic acid, H2bdc = isophthalic acid, 5-OH-H2bdc = 5-hydroxyisophthalic acid, D-H2ca = D-camphor acid), have been hydrothermally synthesized. These compounds were structurally characterized by IR spectroscopy, elemental analysis and X-ray single-crystal diffraction. Compound 1 exhibits a 2D → 3D framework with an unusual parallel polycatenation of corrugated 2D (4,4) nets. Compounds 2–4 are structurally similar and display 2D layer structures, in which 2 and 3 extend into 3D supramolecular frameworks through interlayer O–H⋯O hydrogen-bonding interactions. Compound 5 displays a 3D 2-fold interpenetrating framework with a rare {44·66} sqp topology, containing an interesting ⋯LRLR⋯ double helical layer structure. Compound 6 is a 2D network with {44·62}-sql topology and further extends via C–H⋯O hydrogen bonds into the 3D supramolecular framework. Compound 7 possesses a rare 3D non-interpenetrated cds-type framework with the Schlafli symbol {65·8}. Thermal stabilities for 1–7 and photoluminescence properties of the compounds 3–7 have been examined in the solid state at room temperature. Furthermore, solid-state UV–vis spectroscopy experiments show that compounds 1–7 exhibit optical band gaps which are characteristic for optical semiconductors, with band gaps of 2.41, 2.44, 2.48, 2.46, 2.83, 2.68, and 2.72 eV, respectively.

Improvement of dye-sensitized solar cells performance through introducing different heterocyclic groups to triarylamine dyes

This paper focuses on the structure modification of triphenylamine dyes for efficient dye-sensitized solar cells (DSSCs). Three D–D–π–A dyes (TTR1–3), with triphenylamine moiety and its derivatives as the electron donor, thiophene ring as the π-bridge, and 2-(1,1-dicyanomethylene)rhodanine (DCRD) as the electron acceptor, were synthesized and fully characterized. Nanocrystalline TiO2-based DSSCs were fabricated using these dyes to investigate the effect of different donor groups introduced into triphenylamine on their photovoltaic performances. The overall power conversion efficiency (PCE) of DSSCs based on TTR1–3 with chenodeoxycholic acid (CDCA) coadsorbant are 5.20%, 5.71% and 6.30%, respectively, compared to 6.62% achieved with N719. Introduced heterocyclic group with alkyl lain into triphenylamine decreased dye absorbed amount but significantly improved the value of the open circuit voltage (Voc) and the short-circuit photocurrent (Jsc), which result from the fact that they can effectively suppress the charge recombination and prevent aggregation between adjacent molecules on TiO2. We also researched the effect of sensitization for single dyes on their photovoltaic performances. The PCEs of DSSCs soaked for 32 h increase slightly compared to those of DSSCs soaked for 16 h, which result from the adsorption quantity on the TiO2 surface. We found that, with soaking twice in 32 h, the Jsc and Voc were both obviously improved compared with soaking once in 32 h. These results provide a new approach for enhancing the photovoltaic performances of DSSCs based on single dye.

Syntheses, characterization, and properties of five coordination compounds based on the ligand tetrakis(4-pyridyloxymethylene)methane

A nonplanar tetrahedral pyridine ligand has been synthesized and applied to assemble five metal–organic frameworks (MOFs) with novel structural features under solvothermal conditions, namely, {[Cu2(TPOM)(adi)2](H2O)4}n (1), {[Zn2(TPOM)(glu)2](H2O)8}n (2), {[Cd2(TPOM)(1,4-chdc)2(H2O)4](H2O)4}n (3), {[Ni(TPOM)(suc)(H2O)2](H2O)2}n (4), and {[Zn2(TPOM)(1,4-chdc)(NO3)2](H2O)2}n (5) (TPOM = tetrakis(4-pyridyloxymethylene)methane, adi = adipic acid, glu = glutaric acid, chdc = 1,4-cyclohexanedicarboxylic acid, suc = succinic acid). These compounds were characterized by elemental analyses, IR spectroscopy and X-ray single-crystal diffraction. Compounds 1 and 3 reveal 3-fold interpenetrating 3D frameworks with sqc969 and new topologies, while compound 2 possesses a 2-fold interpenetrating 3D framework with qtz topology. Compound 4 exhibits a non-interpenetrating 3D structure with the extension of the cage structure, in which there are only two pyridine nitrogen atoms in TPOM involved in the coordination. It is different from compounds 1–3, which may take distinct coordination modes under different conditions. In compound 5, the coordination mode of TPOM is also different from those of compounds 1–3; it is a 2D structure with a 2-fold interpenetrating framework.

A triphenylamine-functionalized luminescent sensor for efficient p-nitroaniline detection.

The combination of π-conjugated fluorophores within a hybrid system gives rise to a triphenylamine-functionalized material [Zn(bpba)(NO3)] (1) (Hbpba = 4-(bis(4-(pyridin-4-yl)phenyl)amino)benzoic acid). Compound 1 features a 2D + 2D → 2D parallel polycatenation structure with 63-hcb net. Photophysical studies revealed that the title phase showed superior sensitivity towards p-nitroaniline (p-NA) with a low detection limit (down to ∼0.10 ppm). Specifically, following a new detection route, vapor-sensing experiments using a saturated ethanol solution of nitroaromatic isomers have been established for the first time. Highly sensitive and selective detection of p-NA by the proposed material with a rapid response time (t = 30 s, QE > 90.0%) as compared to that via the control isomers (t = 60s, QE < 6.0%) demonstrates an attractive feasible route and a promising luminescent sensor for nitroaromatic detection.

Two New Isomorphous Zinc(II) and Nickel(II) Supramolecular Coordination Polymers Based on the (benzotriazol-1-yloxy)-Acetic Acid Ligand: Syntheses, Structures, Properties, and DFT Analyses

Two new isomorphous zinc(II) and nickel(II) supramolecular complexes, [Zn(L)2(H2O)2]n, (1), and [Ni(L)2(H2O)2]n (2) {HL = (benzotriazol-1-yloxy)-acetic acid} have been synthesized under ambient conditions by the self-assembly of HL with Zn(Ac)2·2H2O or Ni(Ac)2·4H2O in the presence of triethylamine. The two complexes have been characterized by single-crystal X-ray diffraction, elemental analysis, and IR spectroscopy. Single-crystal X-ray diffraction shows that the two complexes are isostructural and crystallize in monoclinic crystal system P21/c with similar unit-cell parameters and exhibit one-dimensional infinite chain structures. Adjacent chains are linked by O–H⋯O hydrogen bonds, giving rise to a two-dimensional network and these networks are further extended by weak π⋯π stacking interactions among adjacent aromatic cycles of HL ligands into a three-dimensional framework. In addition, the luminescent property of 1 and UV–Visible absorbance of 2 were also investigated and discussed. Density functional theory (DFT) calculations of the structures, stabilities, orbital energies, and composition characteristics of some frontier molecular orbitals of the two complexes were performed by means of Gaussian 09W package and taking B3LYP basis set.